The invention relates to an endoscope system, and more particularly, to an endoscope system for inspecting the gastrointestine or the like.
An endoscope has an flexible inserting tube to be inserted into a human body such as the gastrointestine. The flexible inserting tube bends along the gastrointestine as it is inserted therein. However, the surgeon cannot observe the flexure state of the flexible inserting tube. Therefore the surgeon can hardly decide how to advance or retract the flexible inserting tube within a patient's body.
The flexure state of the flexible inserting tube may be observed by means of fluoroscopic apparatus, however, x-ray radiation should be done in a room having a thick wall of lead. Further, radiation dose increases with continuous x-ray radiation and causes a deleterious effect on the patient. Therefore, detection of the flexure state of the endoscope in a more simple and safe manner is required.
There are endoscope systems which detect the position of the tip end of the inserting tube without using the x-ray radiation, such as the endoscope system disclosed in Japanese Patent No. 2959723 by which a magnetic field generating member is mounted to the tip portion of the flexible inserting tube to allow detection of its location by means of magnetic sensors. This system, however, detects only the position of the tip of the flexible inserting tube, but not the flexure state of the entire inserting tube. Further, the detection of magnetic field is easily affected by background noises and therefore the system mentioned above cannot detect the location precisely.
There are also endoscopes provided with a convex type ultrasonic probe at the tip end of the flexible inserting tube to obtain an ultrasonic tomogram. The convex type ultrasonic probe scans ultrasonic pulses within a scanning plane which includes the longitudinal axis of the tip portion of the flexible inserting tube. Centesis by means of puncture needle, for example, can be performed safely, that is, without penetrating blood vessels with the puncture needle, by sticking out the puncture needle from the tip portion of the flexible inserting tube along the scanning plane so that the puncture needle can be observed to check the location in real time on the ultrasonic tomogram.
There are, however, blood vessels not extending along the scanning plane but crossing the scanning plane. Such blood vessels appears as small points on the ultrasonic tomogram and could be overlooked by the surgeon.
The location of such kind of blood vessels can be recognized if a three dimensional ultrasonic tomogram is generated as in the endoscope system disclosed in Japanese Patent Application Provisional Publication HEI6-261900.
The endoscope system of HEI6-261900 is provided with a radial type ultrasonic probe which scans the ultrasonic pulses in radial direction with respect to the longitudinal axis of the tip portion of the flexible inserting tube. The use of radial type ultrasonic probe facilitates the generation of the three dimensional tomogram. However, the puncture needle cannot be observed on the ultrasonic tomogram at real time since the puncture needle cannot be stuck out from the flexible inserting tube along the scanning plane. Accordingly, the endoscope system of HEI6-261900 may still penetrate blood vessels with the puncture needle and thereby cause bleeding.
Further, the endoscope system of HEI6-261900 also detects the position and attitude of the ultrasonic probe by means of a magnetic sensor provided in the vicinity of the ultrasonic probe. Therefore, the accuracy of detected attitude of the probe, and in turn the accuracy of the three dimensional ultrasonic tomogram is relatively low.